Along with increasingly high integrity of mobile terminals, taking cell phones as an example, cell phones have powerful capabilities of handling information and may provide color screens and video cameras with proper resolutions and colors. A new Radio Access Network (RAN) technology may provide a bandwidth high enough for wireless data transmission. Subsequently, cell phones begin to provide various applications, such as multimedia short message service, Packet Switch (PS) domain video stream service, videophone service, and Multimedia Broadcast Multicast Service (MBMS).
Among the services mentioned above, the first three services need a radio network to provide a bearer for point to point transmission, and the Multimedia Broadcast Multicast Service needs a radio network to provide a bearer for point to multipoint transmission. Transferring point to multipoint services over a network was not considered when the R99 and R4 protocols of the 3rd Generation Partnership Project (3GPP) of the Universal Mobile Telecommunication System (UMTS) network were established. MBMS has been involved in the R6 version protocol, and correspondingly, more functions of core network and access network have been added in the R6 protocol to provide a bearer for point to multipoint transmission. A new node Broadcast Multicast-Service Center (BM-SC) is added outside the core network and coupled with a Gateway GPRS Support Node (GGSN). The BM-SC provides Multimedia Broadcast Multicast Services, and implements the access control and charging of mobile terminals in a multicast service. New functions are supplemented to the user planes and control planes of GGSN, Serving GPRS Support Node (SGSN), Radio Access Network (RAN), and cell phones to assist the BM-SC in providing point to multipoint services. FIG. 1 is a simplified conventional schematic diagram illustrating a relevant network structure in the WCDMA network.
A TV function of cell phone enables users to directly watch TV programs on cell phones so that the users may watch TV programs at any place and at any moment. An investigation shows that the TV function of cell phone holds great attraction to the users. The TV function is one of Multimedia Broadcast Multicast Services, and it could be directly provided in an R6 product in which a Multimedia Broadcast Multicast Service is implemented. However, the establishment of the R6 protocol has not yet been completed, and it will take some time to push well-developed products into markets.
Now, products in WCDMA R99 and R4 protocols are available. The products may provide users with live broadcast services or on-demand broadcast services in a point to point stream media mode, which may result in a high cost of the services, a limited number of users of cell phone TV, a high service fee, and a low commercial value.
In the WCDMA R5 protocol, High Speed Downlink Packet Access (HSDPA) is introduced into a RAN side, which increases capability to handle data on the RAN side. A 3-sector NodeB is capable of handling traffic of data of tens of megabits. There are a lot of applications based on multicast, for example, Internet protocol television (IPTV), video live broadcast, and network radio in the conventional network, and more applications based on the stream media are provided for users. A RAN will function as a high-powered data router plus its conventional functions. At present, however, the RAN cannot support the multicast handling of IP data with respect to live broadcast services.
Current mainstream communication mobile networks such as WCDMA, CDMA2000, GSM, or TD-SCDMA are not sufficient to support an IP multicast function. There is a relevant MBMS protocol in the R6 protocol of WCDMA, but it is rather complex and difficult to implement an MBMS protocol with hierarchy from a higher layer to a lower layer. FIG. 2 illustrates a simplified process of implementing an MBMS service in R6 protocol of WCDMA.
As shown in FIG. 2, an Internet Group Management Protocol (IGMP) join request from a User Equipment (UE) is sent to a Gateway GPRS Support Node (GGSN). The entire MBMS service procedure is initiated by the GGSN, and the entire modification involves a plurality of network elements. Along with the constant development of IP networks, there will be a large number of IP multicast data sources (e.g. IPTV) on the Internet. It will be difficult for the UE to transparently access these IP multicast data sources through an R6 MBMS.
In a network supporting current WCDMA R99 and future R4 and R5 protocols, a stream media service is transmitted on the RAN side in a point to point mode. Unfortunately, the resources for transmission between a NodeB and a Radio Network Controller (RNC) are rather limited. Because there is a wide range of the distribution of NodeBs, not all NodeBs have a condition for the laying of optical fiber or a plurality of E1s, and the cost of the laying is quite high. Moreover, for operators without resources for transmission, the price for renting the resources for transmission is also quite high. In the case of a stream media live broadcast service, one operator usually provides only a few of live broadcast channels (for example a few sets of TV programs) due to limited program channels. If, meanwhile, dozens of users under a NodeB are watching the program of the same TV channel, it is necessary to establish for each user a transfer channel for carrying the stream media service data, thus a large number of IUB interface resources are occupied. For this reason, the operators have to increase resources for transmission so as to deal with the insufficiency of IUB interface bandwidth.
A better way that saves bandwidth is to implement an IP multicast function. The IP multicast function provides that, when a plurality of UEs access the same live broadcast program, it is preferable to send only one copy of data at each interface of a mobile network. At present, there is no IP multicast technique implemented for a WCDMA network according to protocols R99, R4 and R5. It is necessary to establish a dedicated channel at each interface of WCDMA system for each user so that users may enjoy a stream media live broadcast service. The same data is sent many times, resources are used ineffectively, and the number of users is limited.
For a stream media live broadcast service, because a dedicated channel is adopted for an air interface, and there are only a couple of limited users that may be served by each cell, the charging of the stream media live broadcast service run by the operator is very high, and the stream media live broadcast service may not be popularized.